1. Field of the Invention
This invention relates to a method for the production of an esterified product and an apparatus therefor. More particularly, the invention relates to a method for efficiently producing a (meth)acrylic ester (occasionally referred to briefly as xe2x80x9cesterified productxe2x80x9d in the present specification) of high quality by the esterification reaction of an alcohol with (meth)acrylic acid, and to an apparatus therefor. Especially, in quantity production of an esterified product on a commercial scale by continuous operation of an apparatus for production, this invention relates to a method for the production of the esterified product excelling in production efficiency, and the apparatus therefor.
2. Description of the Related Art
A varying alkoxy polyalkylene glycol mono(meth)acrylic ester type monomer component which forms a raw material for a polymer component to be used in cement dispersants, and pigment dispersants for calcium carbonate, carbon black, ink, and other pigments, scale removers, dispersants for a slurry of gypsum and water, dispersants for CWM, thickeners, and etc. can be obtained by subjecting an alkoxy polyalkylene glycol and (meth)acrylic acid to the esterification reaction. Since this esterification reaction by-produces water simultaneously, the reaction which is equilibratory in nature ceases to proceed in the direction of forming the esterified product unless the water formed by the reaction is removed from the reaction system (namely when the water formed by the reaction is suffered to accumulate therein).
As found in Controls 1 and 2 cited in JP-A-09-328,346, for example, the synthesis of a varying alkoxy polyalkylene glycol mono(meth) acrylic ester type monomer component which forms a raw material for a polymer component to be used in a cement dispersant resorts to a principle of providing a water separator for accomplishing the separation of the water formed by the reaction. More specifically, this publication discloses a method for synthesizing an expected esterified product by using a reaction vessel designed for the synthesis of an alkoxy polyalkylene glycol mono(meth)acrylic ester type monomer by the esterification reaction and adapted to permit separation of the water formed by the reaction by providing a reaction vessel (a separable flask) with a thermometer, a stirrer, and a water separator, performing the esterification reaction by placing methacrylic acid, methoxy polyethylene glycol (an average addition mol number of oxyethylene groups of 10 mols), sulfuric acid (Control 1) or paratoluene sulfonic acid (Control 2) as an acid catalyst, phenothiazine as a polymerization inhibitor, and cyclohexane as a solvent in the reaction vessel and meanwhile stirring and heating the reactants and consequently effecting distillation of a cyclohexane-water azeotropic mixture under normal pressure, removing the water formed by the reaction with the water separator, and refluxing the cyclohexane, and after the completion of the esterification reaction, expelling the used cyclohexane by distillation.
No technical tasks other than the idea of providing a water separator for separating and removing the water formed by the reaction during the course of the esterification reaction or the idea of expelling a dehydrating solvent by distillation after the completion of the esterification reaction using a dehydrating solvent as disclosed in the patent publication mentioned above has heretofore been reported to the literature.
An object of this invention, therefore, is to solve the technical problems of the prior art and to provide a method for the production of an esterified product and an apparatus therefor.
Another object of this invention is to provide a method for the production of an esterified product which prevents the occurrence of a gel-like substance during the separation and removal of the water formed by the reaction by causing an antigelling agent to act on the distillate and consequently permits efficient production of the esterified product of high quality, and an apparatus therefor.
Still another object of this invention is to provide a method for the production of an esterified product which prevents the occurrence of a gel-like substance during the expulsion of a dehydrating solvent by distillation after the esterification reaction and consequently permits efficient production of the esterified product of high quality, and an apparatus therefor.
Further object of this invention is to provide a method for the production of an esterified product by the esterification reaction of an alcohol and (meth)acrylic acid which always prevents effectively the occurrence of a gel-like substance on a path for expulsion by distillation by causing a sufficient amount of an anti-gelling agent-containing solution to act on the distillate and consequently permits efficient and inexpensive formation of the esterified product of high quality, and an apparatus therefor.
Still further object of this invention is to provide a method for the production of an esterified product which, when a dehydrating solvent is used in the production of the esterified product, represses growth of an amount of a residue of condensate returned to a reaction tank besides fulfilling the object mentioned above as small as possible by causing a sufficient amount of an antigelling agent-containing solution to act on the distillate and consequently permits efficient and inexpensive formation of the esterified product of high quality, and an apparatus therefor.
The prevent inventors, while continuing a diligent study with a view to attaining efficient formation of an esterified product of high quality, have found that a gel-like substance is formed during the condensation of a distillate arising from the esterification reaction (an azeotropic mixture of a solvent with water formed by the reaction) and that this gel-like substance gives birth to numerous technical problems as evinced by the fact that a part of this gel-like substance, on being refluxed in conjunction with the solvent, persists as an extraneous substance in the reaction tank, mingles into a finished product (for example, a cement dispersant, a pigment dispersant, a scale remover, a dispersant for a slurry of gypsum and water, a dispersant for CWM, and a thickener), and forms a cause for degrading the performance and quality of the product, that the gel-like substance, when the esterified product is produced in a large quantity on a commercial scale, cumulatively adheres to the inner wall of a piping and a device (for example, a condenser), i.e. means for condensing, separating, and removing water formed by the reaction, and eventually induces possible degradation of the heat-exchange efficiency during the condensation, that the deposit of the gel-like substance, when the operation is repeated or continued with a view to attaining quantity production on a commercial scale, impairs the flow of the fluid (mainly the liquid resulting from the condensation) in the condenser and the piping, possibly induces clogging thereof, and consequently compels the operation to be periodically suspended for permitting removal of the gel-like substance from the interior of the condenser and the piping by washing.
The present inventors have further found that the expulsion of the dehydrating solvent to be effected in the form of an azeotropic mixture with added water after the completion of the esterification reaction by the use of a dehydrating solvent reflux system fulfilling the purpose of separating and removing the water formed by the reaction forms a gel-like substance besides the gel-like substance formed during the esterification reaction and that the distillate containing this gel-like substance, when suffered to reach the step of polymerization and eventually mingle into the finished product (for example, a cement dispersant, a pigment dispersant, a scale remover, a dispersant for a slurry of gypsum and water, a dispersant for CWM, and a thickener), degrades the performance and quality of the product in the same manner as described above.
The present inventors, therefore, have continued a diligent study in search of a solution for the problems mentioned above and also a method for efficiently forming an esterified product with high quality and have consequently ascertained themselves that a gel-like substance to be generated during the separation and removal of water formed by the reaction or during the expulsion of a dehydrating solvent by distillation consists mostly of a poly(meth)acrylic acid and that this gel-like substance is formed (as gelated by a liquid-phase reaction) when either of the raw materials, i.e. alcohol and (meth)acrylic acid, for the esterification reaction is used in an excess amount for the purpose of accelerating the esterification reaction or a raw material having a lower boiling point is used in an excess amount for the purpose of facilitating the isolation of the target esterified product by distillation and consequently the raw material of the low boiling point remains in an unaltered form after the completion of the esterification reaction and a part of the unaltered raw material is expelled as an azeotropic mixture with water (an axeotropic mixture of a solvent and water formed by the reaction) or expelled in conjunction with the dehydrating solvent by distillation and then condensed and liquified. On the basis of this mechanism for the occurrence of the gel-like substance, they have discovered a measure for very effectively preventing the occurrence of the gel-like substance mentioned above.
Further, the present inventors have continued a diligent study with a view to solving the technical problem mentioned above and have consequently made a discovery that the technical problem can be solved by utilizing as a solution of an antigelling agent intended to act on the distillate emanating from the reaction tank a solution containing at least a part of a condensate, particularly a mixture of a part of a condensate (especially a part of a residue of condensate remaining after the separation and removal of water formed by the reaction and to be returned to the reaction tank) with a solution of an antigelling agent. The present invention has been perfected as a result.
Specifically, the objects of this invention can be accomplished by a method for the production of an esterified product by the esterification reaction of an alcohol represented by the formula (1):
R1O(R2O)nHxe2x80x83xe2x80x83(1)
wherein R1 represents a hydrocarbon group of 1 to 30 carbon atoms, R2O represents an oxyalkylene group of 2 to 18 carbon atoms, providing that the repeating units, R2O, may be the same or different and that when the R2O""s are in the form of a mixture of two or more species, the repeating units, R2, may be added either in a block form or in a random form, and n represents an average addition mol number of oxyalkylene groups and is in the range of 0 to 300, with (meth)acrylic acid, wherein said method comprises acting an antigelling agent on a distillate.
The objects of this invention can be also accomplished by a method for the production of an esterified product by the esterification reaction of an alcohol represented by the formula (1):
R1O(R2O)nHxe2x80x83xe2x80x83(1)
wherein R1 represents a hydrocarbon group of 1 to 30 carbon atoms, R2O represents an oxyalkylene group of 2 to 18 carbon atoms, providing that the repeating units, R2O, may be the same or different and that when the R2O""s are in the form of a mixture of two or more species, the repeating units, R2O, may be added either in a block form or in a random form, and n represents an average addition mol number of oxyalkylene groups and is in the range of 0 to 300, with (meth)acrylic acid in the presence of a dehydrating agent, wherein said method comprises expelling by distillation water formed during the esterification reaction in conjunction with the dehydrating solvent, condensing and liquefying the distillate containing the water, separating and removing the water from the condensate resulting from the condensation and liquefaction, and returning to a reaction tank a residue of condensate containing the dehydrating solvent and remaining after the separation and removal of the water, and causing an antigelling agent solution containing a part of the residue of condensate and an antigelling agent to act on the distillate during the course of the esterification reaction.
The objects of this invention can be further accomplished by a method for the production of an esterified product by the esterification reaction of an alcohol represented by the formula (1):
R1O(RO)nHxe2x80x83xe2x80x83(1)
wherein R1 represents a hydrocarbon group of 1 to 30 carbon atoms, R2O represents an oxyalkylene group of 2 to 18 carbon atoms, providing that the repeating units, R2O, may be the same or different and that when the R2O""s are in the form of a mixture of two or more species, the repeating units, R2O , may be added either in a block form or in a random form, and n represents an average addition mol number of oxyalkylene groups and is in the range of 0 to 300, with (meth)acrylic acid in the presence of a dehydrating agent, wherein said method comprises further a step of expelling by distillation the dehydrating solvent after the completion of the esterification reaction while causing an antigelling agent to act on the distillate containing the dehydrating solvent.
The objects of this invention can be furthermore accomplished by an apparatus for the esterification to be used for the method of this invention for producing an esterified product, which comprises a reaction tank for the esterification reaction of an alcohol represented by the formula (1):
R1O(R2O)nHxe2x80x83xe2x80x83(1)
wherein R1 represents a hydrocarbon group of 1 to 30 carbon atoms, R2O represents an oxyalkylene group of 2 to 18 carbon atoms, providing that the repeating units, R2O, may be the same or different and that when the R2O""s are in the form of a mixture of two or more species, the repeating units, R2O, may be added either in a block form or in a random form, and n represents an average addition mol number of oxyalkylene groups and is in the range of 0 to 300, with (meth)acrylic acid, a condenser for condensing and liquefying a distillate emanating from the reaction tank, an antigelling agent-supplying mechanism disposed at at least one point on a connecting pipe intervening between the reaction tank and the condenser, and a water separator for separating and removing water from the condensate.
Now, the advantages obtained by the method and the apparatus according to this invention will be described below.
Firstly, the advantages enjoyed by the method for the production of an esterified product according to this invention which comprises causing an antigelling agent to act on the distillate during the course of the esterification reaction will be described below.
(1) The method for the production of an esterified product according to this invention, by causing an antigelling agent to act on the distillate, is enabled to prevent the formation of a gel-like substance and prevent the paths in such devices as a condenser and pipes from blockage and protect the resultant esterified product against degradation of quality causable by the reflux of the distillate resulting from separation and removal of water formed by the reaction to the reaction system and protect the finished product such as a cement dispersant formed by using the esterified product against degradation of performance and quality.
(2) Particularly, the method can derive conspicuously the function and effect indicated in (1) above by causing the antigelling agent to act in the region for condensing the distillate.
(3) By the same token, the method can derive more conspicuously the function and effect indicated in (1) above by causing the antigelling agent to act inside the condenser (preferably in the proximity of the top of the condenser column).
(4) The method, by mixing the antigelling agent with a solvent similar in kind to the dehydrating solvent used for expelling the water formed by the reaction as an azeotropic mixture and heating the resultant mixture, is enabled not only to manifest the function and effect indicated in (1) to (3) above but also to obviate the necessity for providing such an additional device as is capable of separating the dehydrating solvent and the solvent used for dissolving the antigelling agent from each other and refluxing the dehydrating solvent exclusively into the reaction system, facilitate the management of temperature in the reaction system, and avoid complicating the control system because the ref lux of all these components into the reaction system induces no change in the composition of the azeotropic distillate emanating from the interior of the reaction system.
(5) The method, when the antigelling agent possesses solubility in the solvent of (4) above and consequently causes the antigelling agent to be dissolved in the solvent and allowed to act thereon, enjoys such advantages as not only manifesting the function and effect indicated in (1) to (4) above but also facilitating the handling of the agent; permitting the agent to act promptly on what results from condensing and liquefying the distillate by the method of contact such as parallel contact; and allowing adoption of various techniques for enabling the antigelling agent to function very efficiently as by blowing the gaseous distillate into the liquid formed by dissolving the antigelling agent in the solvent, for example, and consequently attaining the required contact of the antigelling agent simultaneously with the liquefaction thereof.
(6) The method, when the alcohol of the formula (1), as one of the raw materials, has the average addition mol number, n, of the oxyalkylene group thereof in the range of 2 to 300, is at an advantage in not merely manifesting the function and effect indicated in (1) to (5) above but also affording a monomer component useful as a raw material for a polymer destined to serve as a main component of a cement dispersant as evinced by the fact that the esterified product obtained by the esterification reaction has been deprived effectively of such impurities as a gel-like substance and a cement dispersant made by using this esterified product excels in slump-retaining ability and water-reducing ability as well as in dispersion properties.
Secondly, the advantages enjoyed by the method for the production of an esterified product characterized by performing the esterification reaction meanwhile expelling by distillation the water arising during the esterification reaction in conjunction with the dehydrating solvent, condensing and liquefying the distillate containing the water, separating and removing the water from the condensate resulting from the condensation and liquefaction, and returning to the reaction tank the residue of condensate containing the dehydrating solvent remaining after the separation and removal of the water, and causing an antigelling agent solution containing a part of the residue of condensate and an antigelling agent to act on the distillate during the course of the esterification reaction will be described below.
(a) The method, by causing the antigelling agent solution mentioned above to act on the distillate during the course of the esterification reaction performed by a procedure of expelling by distillation water and a dehydrating solvent which water is formed during the esterification reaction performed in the presence of the dehydrating agent optionally together with an acid catalyst and a polymerization inhibitor, condensing and liquefying the distillate containing the water, separating and removing the water from the condensate resulting from condensation and liquefaction, and returning a residue of the condensate containing the dehydrating solvent remaining after the separation and removal of the water, enjoys similarly to (1) above the advantages of allowing the inner wall surfaces of the pipes and the condenser disposed on the paths of distillation tending to generate a gel-like substance in consequence of the adhesion of liquefied distillate to be always kept in a wet state by supply of an ample amount of the solution containing the antigelling agent thereby affording constant and effective prevention of the occurrence of a gel-like substance on the paths of distillation mentioned above and permitting efficient and inexpensive production of the esterified product with high quality and consequently allowing the finished product such as a cement dispersant formed by using the esterified product to suffer from no degradation of performance or quality.
(b) The product can repress to the fullest possible extent the increase of the amount of the residue of condensate to be returned to the reaction tank and permit efficient and inexpensive production of the esterified product with still higher quality.
(c) The method, particularly by causing the antigelling agent solution to act in the region for condensing and liquefying the distillate containing the water, namely in the region for generating a gel-like substance in consequence of the deposition of the liquefied distillate on the paths for distillation, can efficiently and effectively prevent the occurrence of the gel-like substance and more conspicuously derive the function and effect indicated in (a) and (b) above.
(d) The method, also by causing the antigelling agent solution to act similarly in the proximity of the top of condenser column for condensing and liquefying the distillate mentioned above, can efficiently and effectively prevent the occurrence of the gel-like substance and more conspicuously derive the function and effect indicated in (a) and (b) above.
(e) The method, by causing the antigelling agent to be dissolved in a solvent similar in kind to the dehydrating solvent being used for distilling the water formed by the reaction in the form of an azeotropic mixture, is at an advantage as in (4) above in not only manifesting the function and effect indicated above but also enabling the antigelling agent solution formed by using the antigelling agent to act promptly on what has resulted from condensing and liquefying the distillate, i.e. an azeotropic mixture with the dehydrating solvent, by the method of contact such as parallel contact because it possesses solubility therein. Further, the method facilitates management of temperature in the reaction tank and avoids complicating the control system because the reflux of these components into the reaction tank brings no change in the composition of the distillate emanating azeotropically from the interior of the reaction tank and avoids varying the azeotropic temperature.
Thirdly, the advantages to be enjoyed by the apparatus for producing an esterified product comprising a reaction tank for performing the esterification reaction, a condenser for condensing and liquefying a distillate emanating from the reaction tank, an antigelling agent-supplying mechanism disposed at at least one point on a connecting pipe intervening between the reaction tank and the condenser, and a water separator for separating and removing water from the condensate will be described below.
(A) The apparatus, by disposing the antigelling agent-supplying mechanism at at least one point on the connecting pipe intervening between the reaction tank and the condenser and making it to act on the distillate, can derive the same effects as those indicated in (a) to (e) above. The apparatus is also at an advantage in affording an esterified product effectively deprived of such impurities as a gel-like substance, enabling a cement dispersant made by using this product to excel not only in dispersing properties but also in such service performances as slump-retaining properties and water-reducing properties, and allowing the product to serve as a monomer component useful as a raw material for a polymer as a main component for a cement dispersant.
(B) The apparatus, by disposing as the antigelling agent-supplying mechanism a nozzle part for acting the antigelling agent solution in the proximity of the top of condenser column, namely a site at which the gel-like substance is generated in consequence of the adhesion of the liquefied distillate to the paths of distillation, is enabled to afford efficient and effective prevention of the occurrence of the gel-like substance and consequently manifest the function and effect indicated in (A) above conspicuously.
(C) The apparatus, by having the nozzle part so disposed as to supply the antigelling agent solution upwardly, is enabled to obtain the function and effect indicated in (A) and (B) still more conspicuously.
(D) The apparatus, by being provided as the antigelling agent-supplying mechanism with a first supply route for supplying the antigelling agent solution from the storage part for the antigelling agent solution to the nozzle part and a second supply route for supplying a part of the condensate (particularly a part of a residue of condensate) to the nozzle part, is enabled to obtain thorough the function and effect indicated in (A) to (C) above.
Fourthly, the advantages enjoyed by the method for producing an esterified product characterized by including a step of causing the antigelling agent to act on the distillate containing the dehydrating solvent in the step of expelling by distillation the dehydrating solvent after the completion of the esterification reaction will be described below.
(i) Besides being capable of effectively preventing the formation of a gel-like substance and protecting the paths in the devices such as a condenser and pipes against blockage, the method, when the device adopted during the circulation of the dehydrating solvent during the esterification reaction is utilized also during the expulsion of the dehydrating solvent by distillation, precludes a possibility of the gel-like substance formed during the expulsion of the dehydrating solvent by distillation being brought into the reaction system during the reflux into the reaction system of the distillate remaining after separation and removal of the water formed by the reaction in the subsequent batch of the esterification reaction as experienced in the repeated (or continuously) operation of the apparatus for the production of the esterified product and consequently avoids inducing decline of the quality and performance of the esterified product. The method, as a result, does not allow the finished product such as a cement dispersant made by using the esterified product to suffer any decline in the performance and quality thereof owing to the gel-like substance.
(ii) The method, by causing the antigelling agent to act in the region for condensing the distillate containing the dehydrating solvent thereby enabling the antigelling agent to act very efficiently and effectively on a material inducing the occurrence of the gel-like substance such as the unaltered low boiling raw material contained in the distillate, is enabled to obtain the function and effect indicated in (i) above very conspicuously.
(iii) The method can manifest a function and effect on a par with that indicated in (ii) above because it is capable of allowing the antigelling agent to act very efficiently and effectively on a material inducing the occurrence of the gel-like substance such as the unaltered low boiling raw material contained in the distillate.
(iv) The method, besides being enabled to manifest the function and effect indicated in (i) to (iii) above by causing the antigelling agent to act as mixed with water during the expulsion of the dehydrating solvent and water by azeotropic distillation, is exceptionally advantageous in producing the action in question promptly on the unaltered low boiling raw material dissolved in the water which accounts for the greater part of the distillate being expelled (distilled) azeotropically with water from the solution in the system because the distillate is composed substantially wholly of water.
(v) The method, besides being capable of manifesting the function and effect indicated in (i) to (iv) above because the antigelling agent can be made to act as dissolved in water when the antigelling agent is soluble in water, enjoys such advantages as permitting easy handling of the antigelling agent; permitting the agent to act promptly on what results from condensing and liquefying the distillate by the method of contact such as parallel contact; and allowing adoption of various techniques for enabling the antigelling agent to function very efficiently as by blowing the gaseous distillate into the liquid formed by dissolving the antigelling agent in the solvent, for example, and consequently attaining the required contact of the antigelling agent simultaneously with the liquefaction thereof.
The above and other objects, features, and advantages of the present invention will become clear from the following description of the preferred embodiment.